Can



-April 14, 1942.

A. L. FORSBERG CAN Filed July 29. 1940 2 Sheets-Sheet 1v April 14, 1942- 'l l L. FQRS'BERG 2,279,668

- CAN Y Filed July 29. 1940 2 Sheets-Sheet 2 l 2,795 f jQQ/@ZQZ Patented Apr. 14, 1942 TES CAN

Albin L. Forsberg, Chicago, Ill., assignor to The Warfield Company, a corporation oflllinois Application July 29, 1940, Serial No. 348,293

3 Claims.

This invention relates to a can body, and more particularly to an improved body for a vacuum can opened by removal of a tear strip.

One feature of this invention is that it provides a stronger and more leak-proof can body while retaining the advantages of convenient and easy removal of the tear strip; vanother feature of this invention is that it provides an improved lock seam arrangement for the body of a can having a band of a plurality of layers at the end where the tear strip is removed; a further feature of this invention is that, although the tear strip is substantially within the borders of the band and the lock seam extends through the band, the strip may be readily torn away without any sticking, particularly at its tail end; still another feature of this invention is that the maximum strength of seam at the band is secured while the arrangement is such that the seam may be rendered leakproof by soldering it on conventional automatic machinery; other features and advantages of this invention will be apparent from the following specification and the drawings, in which:

Figure 1 is a side elevation of a completed' can embodying my invention; Figure 2 is a View of the sheet metal blank for forming the can body, after it has been cut to nal shape but before it has been bent or formed in any way; Figure 3 is a view of the same blank after it has been bent at the top to provide the triple layer band, and after the locking portions at the edges have been folded over; Figure 4 is a top edge view of the blank as shown in Figure 3; Figure 5 is a horizontal sectional view of the rolled blank with its edges or locking portions Yhooked tgether; Figure 6 is a fragmentary detailed View, partially broken away onone side, of the edges before they are hooked together; Figure 7 is an elevation of the can body after it has been seamed but before the top and bottom have been placed thereon; Figure 8 is a detailed sectional view along the line 8 8 of Figure '7; Figure 9 is a detailed sectional view of a portion of the blank before it is folded; Figure l0 is a view of the same portion after the first operation in providing the triple layer band; Figure 1l is a view of the same portion folded to provide the band; and Figure 12 is a partial vertical sectional view of the completed can.

The present application discloses and is particularly concerned with improvements on a can body of the general type disclosed and claimed in my earlier copending application, Serial No. 304,823, filed November 16, 1939.

edges be left which might injure the housewife,

and that the position of the lid' when it is replaced on the can be substantially the same as its position before the tear strip was removed. This is particularly true in cans containing a large amount ofl liquid, or where only a small amount is removed when the can is first opened, as is the case with a can of coffee, for example.

Cans have heretofore been made with an annulus of metal forced into the body `after seaming it, to provide al shoulder for frictionally retaining the lid after the tear strip has been removed; and cans have heretofore been provided with bands of triple layer thickness near theupper end so that .the upper fold of this band becomes the shoulder on which the lid rests after the can is opened. The first type of can, with the annulus forced in after seamingrof the can body, is open to the objection that this is a diicult operation; and that parts of the tin coating on the body are chipped off frequently during the insertion of the annulus. The type of can body with the triple layer band has presented considerable seaming troubles, onlyi one such can bodyhaving received commercial acceptance,

even though the idea of a triple layer band is quite old.

The problem with this latter type of can is in providing a leak-tight mechanically strong seam through the band, since it would be obviously impracticable to bend over three layers and hook them into three other similarly bent layers. The can of this type now on the market provides a locked seam for its body only up to the bottom of the triple layer band, and uses a simple overlapping seamk from the bottom of the band to the top of the can. A simple overlapping seam is, of course, much weaker mech-anically than a locked seam; and soldering by a rapid passage of the can body over soldering rolls does not result in certain sealing ofthe seam at the overlap portion where there are so many thicknesses of metal. y

My invention obviates these and other objections by carrying the lock seam completely through the triple layer thicknessband of the can body, so that the only portion of the body held together by a simple overlapping seam is the single thickness relatively narrow part between the top of the band and the top of the can. I have solved the problem of carrying the lock seam through the band by having one of the layers at each edge of the band project beyond the others, so that the interlock is between single layers of metal only even at the band portion where there is a plurality of layers; by notchng back one edge betwen the lines of weakness dening the tear strip; by having the portion of the can blank forming the middle layer of the triple layer band, at this saine edge, ter-y minate in line with the fold line of the hooking portion; by cutting away the portion under the tongue at the other edge of the blank for a certain distance, and beveling the lower edge of this cut; and by slitting the line of weakness at the upper edge of the tongue to at least a certain depth.

The particular embodiment of my invention illustrated herewith is a can generally used for packing food products under vacuum, as coffee. The can comprises as its principal parts a tubular body I0, a lid II, and a bottom I2. As may be best seen in Figure 12, the lid is locked to the upper end of the can body and sealed by conventional means as sealing compound; and the bottom is permanently sealed to the lower end of the body. Still referring particularly to Figure 12, it will be seen that circumferential parallel lines of weakness I3 and I4 denne a tear strip, this tear strip being substantially wholly within and forming the principal part of the outer layer of a triple layer fold. The tear strip is here identified as A, the middle fold as B and the back fold of the band as C. It will be readily apparent that when the tear strip is removed the lid becomes a frictionally retained one, not

changing its position; and that when the lid is removed there is a smooth upper edge with no jagged or raw portion which might injure the hands of the housewife or other user of the can. Referring now more particularly to the blank as shown in Figure 2, this is a sheet of metal cut in the nished form, as by a die-stamping operation. The major portion of each edge of the blank comprises portions I5 and I6 which are to be folded back and forward (inwardly and outwardly of the finished can, respectively), as may be best seen in Figure 4. These have a depth of approximately one-eighth of an inch, and extend from the line of fold which will define the top of the triple layer band to substantially the bottom of the blank, only suflicient space being left beneath to provide a portion for flanging out and attachment to the can bottom. That is, speaking with respect to Figure 2, the locking portion I6 extends from the shoulder I'I (the line at which the fold between the layers B and C is made) to the slit I8; and the locking portion I5 on the other edge extends from the upper portion of the sloping shoulder I9 to the bottom shoulder 20, having a depth equal to that of these shoulders. Referring now first to the left hand edge of the blank, the edge opposite to that from which the tear strip tongue projects, it will be seen that the portion between the lines of weakness is notched back to a depth double that of the locking portion I5 on this edge; and that the portion of the edge which is in the middle layer B of the band, extending from the bottom line of weakness to the shoulder I'I, terminates at the line of bending or folding of the locking portion I6. The upper edge of the can above the line of weakness I3 extends almost but not quite out to the edge of the locking portion I6 in its flat position. Turning now to the right-hand edge of the can, it will be seen that the part of this edge below the tongue 2| is cut back to a depth equal to that of the locking portion I5, terminating at the top edge of the sloping shoulder I9; and the can body is slitted in along the upper line of weakness I3, at the top of the tongue 2|, to a depth at least equal to and preferably slightly greater than the depth of the locking portion I5. This is desirable in order to permit the tongue to be bent up out of the way in one stage of the forming operation, where a die bumps down and locks the two portions I5 and I6 together.

-After the blank is in the position shown in Figure 3 it is formed into a cylinder by forming rolls, and then the portions I5 and I6 are hooked together, as shown in Figure 5. Next the tongue 2| is bent back out of the way and a die presses the seam together to tightly lock the portions I5 and I6 on each other, as best shown by the detail sectional illustration in Figure 8. It will be noted that the die and inner horn at the locking stage cooperate in such a way as to result in the two edges of the seam being flush on the outside of the can. The can is then passed over soldering rolls to solder the seam and the tongue is finally bent back to proper position and the edges of the body flanged outwardly, as shown in Figure 7. The putting on of the top and bottom of the can, its filling, evacuating and the like, all follow conventional procedure.

The resultant nished can has a lock seam extending from the body up to and through the triple layer band, the locking portion I6 terminating in a straight edge and the locking portion I5 extending clear up to the top of the band but terminating in a beveled or sloping edge. Because of this arrangement the outer corner of the top edge of the locking portion I 6 folds down in over the sloping edge at the top of the locking portion I5 to insure better soldering and sealing at this point; yet there is a hook grip between the edge ofthe locking portion I6 and the fold of its cooperating locking portion clear up to the top of the triple layer band. Having the tear strip portion notched back to double the depth of the locking portion (on the end opposite the tongue) enables the locking portion I5 to lie in a recess at this end of the triple layer band, as may be best seen in Figures 6 and 8. Terminating the portion below this notchedaway portion at the line of fold of the locking portion I6 enables only the single layer of metal to be folded, without the necessity of the heavy fold that would result from bending over two thicknesses. Folding the locking portion of the tongue edge of the blank inwardly and the other locking portion outwardly (speaking with respect to the nished can body) and placing them both on the inner layer of the band results in the joint arrangement best seen in Figure 8. This provides a solid, strong, leak-proof joint, yet does not prevent easy removal of the tear strip. The tongue portion 2| stands out where a key can readily be slipped over it, and it tears away without any diiculty at the beginning. Moreover, it is not locked under any other layers of metal in the end, a difliculty usually found with this type of can. It will be noticed that the tail end of the tear strip portion (the outer layer in Figure 8) does not go under the lock seam or under any other metal, but is merely held in place by a solder attachment which can be easily broken. Carrying the edge of the blank above the tongue 2l forward over its cooperating portion to a distance extending beyond the lock seam results in a good solder seal at the upper edge of the lock seam where it merges with the lap seam above the band, another problem which has heretofore presented diiiculty.

This can provides a considerable improvement over similar cans heretofore in use in that it can be more readily formed on conventional machinery; a single mechanical soldering operation, without hand soldering following, results in better sealing and a very much smaller percentage of rejects because of leakage; and carrying of the lock seam clear through the triple layer band provides a mechanically smaller joint in the place where this strength is needed, particularly when the tearing operation is being started.

While I have shown and described certain embodiments of my invention, it is to be understood that it is capable of many modifications. Changes, thereforel in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claims.

I claim:

1. A can body formed by joining the edges of a sheet of metal, the sheet being for the major part in a single layer but having a band of a plurality of layers near one end, the outer layer of the band having circumferential parallel lines of weakening therein forming a tear strip lying substantially withinthe bordersof the band, the

strip projecting beyond one edge of the sheet to provide a tongue and being notched back at the other edge, the means joining the edges including a lock seam extending from the lower end of the body uninterruptedly through the band, the locking engagement at the band being only between single layers extending beyond the other layers, the edge provided with the tongue being outside the other edge when the body is seamed and the locking portion on this edge being a part of the inner layer at the band and turned inwardly, the depth of the notch where the strip is notched back being double the depth of the locking portion on this same edge, whereby the tail end of the tear strip is not gripped beneath one of the locking portions and readily comes free from the remainder of the can when said strip is torn oir.

2. A can body formed by joining the edges of a sheet of metal, the sheet being for the major part in a single layer but having a band of a plurality of layers near one end, the outer layer of the band having circumferential parallel lines of weakening therein forming a, tear strip lying substantially within the borders of the band, the means joining the edges including a lock seam from the lower end of the body through the band, the locking engagement at the band being only between single layers extending beyond the other layers, the tear strip projecting beyond one edge of the sheet to provide a tongue coincident with such strip, this edge being cut away beneath the tongue for a distance at least the width of the band and slit along the upper line of weakness to a depth at least equal to that of the locking portion on this edge, whereby starting of the tearing operation is facilitated.

3. A can body formed by joining the edges of a sheet of metal, the sheet being for the major part in a single layer but having a band of a plurality of layers near one end, the outer layer of the band having circumferential parallel lines of weakening therein forming a tear strip lying substantially within the borders of the band, the means joining the edges including an unbroken lock seam from the lower end of the body through the band, the locking engagement at the band being only between single layers extending beyond the other layers, one edge of the sheet hav'- ing a tongue coincident with the tear strip projecting therebeyond, the locking portion on thisV edge being a part of the inner layer at the band Y and beingvturned inwardly, this edge being cut away beneath the tongue for a distance atleast the width of the band and slit along the upper line of weakness to a depth at least equal to that of the locking portion on this edge, the other edge of the sheet being notched back, between the lines of weakness, double the depth of the locking portion on the same edge, the portion immediately beneath the tear strip and forming the mlddle layer of the band terminating at the line of fold of the locking portion, which is on'the inner layer and turned outwardly on this edge.

ALBIN L. FORSBERG. 

